The most common endogenous cause of rushing's syndrome is Gushing's disease
. Frequent clinical findings include weight gain, truncal obesity, striae,
hypertension, glucose intolerance and infections. Cranial nerve II may be a
ffected by enlarging pituitary adenomas in Gushing's disease; cranial nerve
s Iii, IV and VI may also be affected. The evaluation of patients with susp
ected Gushing's disease and syndrome requires an understanding of the prope
r use and limitations of the tests commonly included in the diagnostic work
-up. The best screening test for Gushing's syndrome is a 24-hour urine coll
ection with analysis for urinary free cortisol excretion. Low-dose and high
-dose dexamethasone suppression tests, corticotropin assays, a corticotropi
n-releasing hormone stimulation test and inferior petrosal sinus catheteriz
ation may be required for a definitive diagnosis. Magnetic resonance imagin
g is useful in localizing the lesion. Surgical removal of the lesion by a t
ransphenoidal approach is usually successful, but long-term follow-up is re
quired. Some patients require,lifetime glucocorticoid replacement therapy.